I've always believed, personally, that bad things happen in order to teach people. It might be considered evil that a child gets burned if he plays with fire (one argument that people have is that God existed, why do bad things happen?) but if he learns from that experience NOT to play with fire, he has come out of the experience with a good, probably life-long, lesson. With that sort of outlook, good can be found in most evil situations. 9-11 is another example of this on a bigger scale.